Since the inception of mobile intensive care ambulance systems more than a decade ago to provide early advanced life support for patients with cardiac arrest or acute myocardial infarction, there has been no single community prospective study to document its value in saving lives. Despite costing over a million dollars to implement in any moderate size community, the benefit derived from such a program has been supported only by retrospective studies. Recently we have documented prospectively the outcome of patients with cardiac arrest or acute myocardial infarction transported by a conventional ambulance system equipped to provide only basic life support (closed chest cardiac massage and intravenous fluid administration without drugs or defibrillation). This study took place over a five month period in Durham County, N. C. (population greater than 150,000) and involved over 1,000 patients during a 16-month period. In this same community, a mobile intensive care system providing advanced life support is scheduled to begin October 1, 1980. Using an already established information gathering system and the above study patients stored on the computerized Duke Data Bank, we propose to document prospectively the effectiveness of mobile intensive care. Specifically, we will compare the morbidity and mortality rates for patients with cardiac arrest and acute myocardial infarction transported by the two ambulance systems. Additionally, we will attempt to identify high risk subsets of patients with cardiac events benefited by mobile intensive care.